Vehicle brake



y 1941- v F. J. TARRIS 2,243,229

VEH I CLE BRAKE Filed July 1, '19s? 2 Sheets-Sheet 1 izvantaz' May 27, 1941. F. J TARl-ls 2,243,229

VEHI OLE BRAKE Filed July 1, 1937 2 Sheets-Sheet 2 Patented May 27, 1941 vnmoma BRAKE Frederick John Tarris, Silvertown, London, England, assignor to The India Rubber, Gutta lPercha and Telegraph Works Company Limited, London, England, a British company Application July 1,.1937, Serial No. 151,489 In Great Britain July 3, 1936 7 Claims.

The present invention comprises improvements in or relating to vehicle brakes and relates more particularly to brakes intended for use with the landing wheels of aircraft. The invention is, however, capable of employment in the braking mechanism of any other wheeled vehicle, and is applicable to a form of brake mechanism comprising a tubular member capable of expansion and contraction under the action of fluid pressure to produce movement of one or more friction elements mounted together with the tubular member within a supporting member having the form of a trough, said movement serving to apply or release the brake mechanism by establishing or disestablishing frictional contact between the aforesaid friction element or elements and one or more co-operating members, such as a brake drum. This form of brake mechanism will be referred to hereinafter in the present specifica tion as a vehicle brake mechanism of th type described.

It has already been proposed in prior forms of construction of a vehicle brake mechanism of the type described, to employ resilient spring parts for effecting a return movement of friction elements to an inoperative position after they have been moved by the action of an expansible tubu-.

lar member to apply the brake. I

The present invention provides in or for a vehicle brake of the type described, the combination with the tubular member, the friction element or elements moved thereby and the supporting trough, of a plurality of resilient spring parts which are located wholly within the supporting trough in spaced relation along the length of the tube and which are such as toexert a spring pressure for the purpose described on the friction element or elements at about the midpoint considered in a direction transversely of the tube.

The present invention provides also in or for a vehicle brake of the type described, the combination with the tubular member, the friction element or elements moved thereby and the supporting trough, of a plurality of resilient spring parts which are located in spaced relation along the length of thetube and tend normally to retain the tube and friction elements in an inoperative condition and which are arranged to extend transversely of the supporting trough and have their ends located and retained at the side walls of the trough or by members secured thereto.

move upon operation of the expansible tubular member and are preferably also provided with transverse slots in' which strip or single leaf springs constituting the resilient spring parts are located.

As will be more readily understood hereinafter the resilient spring parts are. deformed upon operation of the brake mechanism andthey serve positively to return the friction element or elements together with the expansible tubular member to the normal inoperative position upon release of the braking pressure. It will also be understood that the spr ng pressure exerted on the friction element or elements by the resilient spring parts is for the purpose of helping to counteract the increase of pressure at about the mid point considered in a directiontransversely of the expansible tube when the latter is inflated due to the circular shaping of the tube. In order that the invention may be more clearly understood, preferred constructional examples for use in combination with aircraft wheels will be described with reference to th accompanying drawings, in which- Figure lis a central diametrical section through an assembly embodying theinvention and suitable for location within a cylindrical brake drum,

Figure 2 is a View in perspective of part of an assembly similar to that shown in Figure 1 but with a modified form of supporting trough,

Preferably, the resilient spring parts directly engage the friction element or elements which Figure 3 is a view in perspective of the apparatus shown in Figure 2 with the friction elements I removed, I

Figure 4 is a view in perspective of the end portion of one form of friction element,

Figure 5 is a view similar to Figure 4 of a. modifled form of friction element,

Figure 6 is a view of the portion of friction element shown in Figure 5 with some of the friction material removed, and

Figure 7 is an under view in perspective of the end portion of the friction material employed in the friction element shown in Figure 5.

Like reference numerals are employed to denote like parts in the several figures of the drawings.

The assembly shown in Figure 1 comprises a circular supporting trough 8 having the open end of the trough facing radially outwardly. The trough 8 is of aluminium or other light metal such as "Duralumin. This trough is intended to be mounted rigidly with the frame of the aircraft or with the axle upon which the aircraft wheel rotates, and the total assembly will normally be enclosed by a cylindrical brake drum. The supporting trough 8 is formed below its base with an inwardly-extending annular flang 8 enabling the trough to be mounted in position. The flange 8 base ofthe supporting trough 8 for the purpose of preventing grease from running down from the axle of the wheel to the brake mechanism; In the case of the supporting trough 8 shown in Figures 2 and 3, the outer side wall of the trough is also extended to form a flange. serving to exclude mud and water from the brake mechanism when the vehicle provided with the mechanism is in use. The trough 8, as shown in each of Figures 1 to 3, has a base |2 reinforced by ribs l3 extending from the grease-guard l to a flange l4 extending radially inwardly from the free inner edge of the base l2. The inner side wall l5 of the trough 8 is formed as a detachable ring secured to the flange M by means of bolts I8. I A'flattened rubber tube preferably covered In the present'con'struction adjacent and contiguous edges of successive-friction elements 2|- are transversely slotted between their cut-away corners to form recesses or slots 25 extending with fabric as at I8, is supported with one flattened surface of the tube in contact with the innersurface of the base |2 of the supporting trough. The tube is in the form of an endless ring and a pipe connection I9 is. provided to pass through the base l2 of the trough 8 and communicate with the interior of the rubbertube An adaptor 28 is conveniently associated with the pipe connection H! for enabling the latter to be connected to a fluid pressure supply.

The outer cylindrical surface of the-flattened rubber tube is in contact with the undersides of a series of, small friction elements 2| which are pressed outwardly into contact with the internal surface of a brake drum when the tube I1 is inflated by fluid pressure passed through the-adaptor 28 and pipe connection [9; The friction elemeii'ts 2| are formed of any preferred material, for example fibrous and coarsely woven material impregnated with a synthetic resin.

The side walls of the supporting trough 8 are stepped at-22 to form a seating for the friction elements 2| when they are in their inoperative,

position. The friction'elements 2|. are held in position by means of resilient spring parts 23 which are in the form of strip or single leaf springs. j

The single leaf springs 23 extend transversely of the supporting trough 8 and have their ends located in cut-away portions of locating blocks 24 secured to the inner surface of the side walls of the supporting trough 8. The cut-away portions of the locating blocks 24 afford recesses for the ends of the resilient parts 23 along the inner surfaces of the side walls of the supporting trough 8, and said cut-away portions are provided along the lower edges of the locating blocks so that the latter straddle the ends of the spring parts 23 to prevent outward movement .of said ends. 1

The friction elements 2| are in the form of rectangular tablets curved to the circular shape of the supporting trough 8 and enclosing brake drum (not shown), the corners of the tablets being. cut away as seen more clearly from Figures 4 to 7 to form lateral recesses which accommodate the locating blocks 24. The 'inwardly projecting blocks 24 thus serve to ,prevent rotational movement of the friction elements 24 relatively to the supporting trough 8 in a manner similar to one which has already transversely across the ends of the blocks. See Figure 4. The sides of the slots 25 are substantially parallel to the friction face of the elements 2| and the resilient spring parts 23 are housed in the slots.' With this arrangement it is possible for each resilient spring part 23 toengage a pair of successive friction elements 2| so that the latter are subjected to the action of the spring parts 23 at each end of each element. The resilient spring parts 23 are conveniently enlarged laterally at their mid por-' tions andthe slots in the friction elements may be shaped internally to receive such enlargement.

When the brake is to be applied, liquid or gas pressure is allowed to pass through the adaptor 28 and the pipe connection l9 into the rubber tube which moves somewhat out of its flattened condition and presses the friction elements 2| radially outwardly against the friction lining of the brake drum. This movement of the friction elements 2| and of the rubber tube ll is accompanied by deformation of each of the spring parts 23 at least one end of each of which is located freely within the cut-away portion of the locating blocks 24 securing the springs 23 in place. The transverse leaf springs 23 apply restraining spring pressure at the mid portion of the friction elements 2| considered in a direction transversely of the trough 8 and of the expansible tube II. This spring pressure helps to counteract a tendency for excess pressure supply. It is .to be noted that direct en-' gagement between the transverse leaf springs 23 and the friction elements 2| is obtained with the construction described above, and there is no necessity for rivets to be driven through. the friction material in order to secure the frictionelements 2| in position. Further, it is to be noted also that the resilient spring parts 23 are wholly located within the supporting trough 8 and are in fact totallyenclosed by the trough 8 and by the friction elements 2|.

Further modification of the forms of constructions which have been described may be made for example by providing a metal base for each friction element 2|- as shown in Figures 5 to 7. This metal base for the friction material is seen at 26 and is of substantially rectangular form with its corners cut away to accommodate the locating blocks 24. Upstanding 'side flanges 21 of U-form serve to secure, the metal base to the friction material of the friction element 2|,the final arm of the U takinginto a groove 28 provided along the side edge of the friction material which is shown in Figure 7 removed from the metal base 28. Adjacent end edges of the friction elements afiord the necessary slots to accommodate the resilient spring parts 23, the upper walls of the slots being providedby a. cut-away portion 29 of the friction material as seen in Figure '7. The lower walls of the slots, however, are now provided by adjacent end portions of a pair of metal bases 28. A suitable recess 88 for the central enlarged portion of a leaf spring 23 is preferably cut on the under surface of the friction material of each friction element as seen in Figure '7.

It is to be understood that the invention is also applicable to vehicle brakes operated by means of a vacuum, which form of brakes is intended to be included in the term vehicle brake mechanism of the type described employed in the present specification and referring to brakes comprising a member expansible or deformable under the action of fluid pressure; This fluid pressure may clearly be a positive pressure but is in the case of vacuum-operated brakes atmospheric pressure.

I claim: I

1. For use in a vehicle brake or like frictionally engageable structure comprising a friction surface, the combination of an annular supporting trough, an expansible tube located therein, a plurality of relatively thin friction blocks located in the trough end to end circumferentially thereof between said expansible tube and the friction surface, the said blocks having lateral recesses at their ends, retracting leaf springs each extending transversely of the trough and situated between adjacent friction blocks, and projections which extend inwardly from and at spaced intervals alon the side wall of the trough and engage within said lateral recesses in the blocks.

2. For use in a vehicle brake or like frictionally engageable structure comprising a friction surface, the combination of elements in accordance with claim 1, in which the projections which extend inwardly from the side wall of the trough are themselves provided with recesses to receive the ends of the leaf springs.

3. For use in a vehicle brake or like frictionally engageable structure comprising a friction surface, the combination of elements accordingto claim 1 in which the ends of the friction blocks are formed with recesses extending transversely of part at least of an associated leaf spring.

4. For use in a vehicle brake or like frictionally engageable structure comprising a friction surface. the combination of elements according to claim 1 in which each friction block at each end has a transverse slot extending across its width and in the combined slots of adjacent ends of two neighbouring friction blocks a single leaf spring is substantially completely housed.

5. For use in a vehicle brake or like frictionally engageable structure comprising a fric' tion surface, the combination of elements according to claim 1 in which each friction block comprises a metal base having friction material carried on the outer side thereof and the metal base forms at least one wall of the transverse slot in which the leaf spring is received.

6; For use in a vehicle brake or like'frlctionally engageable structure comprising a friction surface, thecombination of elements according to claim 1 in which each leaf spring is in the form of a strip having an enlarged mid portion and is so curved that'when the extensible tube is deflated the enlarged mid portion of each spring of the blocks for the reception within the recesses 1 beers substantially alone against the friction blocks with which it cooperates at a transverse mid position of the'blocks.

7. For use in a vehicle brake or like frictionally engageable structure comprising a friction surface, the combination of elements according to claim 1 in which each leaf spring has a mid portion formed with an enlargement extending on each side of the spring circumferentially of the trough, andeach friction block in addition to the transverse slot within which an associated leaf spring is accommodated, is formed with a recess shaped to receive within it a corresponding portion of the enlarged part of. the spring. -i

FREDERICK JOHN TARRIS. 

